1. Field of the Invention
The invention relates to vehicle, control system and control method for controlling a vehicle including a three-phase AC motor.
2. Description of Related Art
A method of detecting electric leakage in a three-phase AC motor has been, proposed (see Japanese Patent Application Publication No. 7-241002 (JP 7-241002 A)). According to this method, either the upper arms or the lower arms of an inverter are momentarily placed in the ON state, so as to determine which phase of the three phases suffers from electric leakage.
A system configured to turn on switching devices of phases other than a short-circuited phase, using back electromotive force, when a short circuit is detected has also been proposed (see Japanese Patent Application Publication No. 2013-121256 (JP 2013-121256 A)).
Also, a system that disconnects an arm including a short-circuited phase from a circuit when a short circuit is detected has also been proposed (see Japanese Patent Application Publication No. 2011-155708 (JP 2011-155708 A)). In this publication, it is also disclosed that, when the rotational speed of a motor-generator becomes equal to or higher than a predetermined rotational speed after detection of a short circuit, the three phases of the arms on the short-circuit side are brought into the ON states, so as to lower the current value, thus assuring a thermal advantage.
In the meantime, it is possible to reduce a switching loss of a power converter, by performing particular-phase ON control on the power converter when the vehicle is stopped.
The particular-phase ON control means control for placing all of first switching devices (which are generally called “upper arm” or “lower arm”) or second switching devices (which are generally called “lower arm” or “upper arm”) in the OFF state, and placing at least one of the other of the first switching devices and the second switching devices in the ON state. Namely, the particular-phase ON control includes one-phase ON control in which one phase of the three phases is placed in the ON state, two-phase ON control in which two phases are placed in the ON states, and three-phase ON control in which the three phases are placed in the ON states.